Buttons: types, sizing and sewing them on

Button types

The only structural distinction that matters is what happens on the back. Everything else is decoration.

• Flat (sew-through)

  Back: Two or four holes through the face

  Use it on: Shirts, blouses, light dresses, cardigans, pyjamas — anything in thin cloth.

  Two holes for fine shirting, four for anything that will be pulled. Four holes give you twice the anchor points and let you choose a stitch pattern.

• Shank

  Back: A stem or metal loop on the reverse, no holes through the face

  Use it on: Coats, jackets, thick knitwear, upholstery — anywhere the fabric is bulky.

  The shank lifts the button clear of the cloth so the buttonhole side can sit flat underneath. On a heavy coat, a flat button without a shank strains and eventually tears out.

• Self-shank

  Back: Shank moulded as part of the button body

  Use it on: Coats and jackets, and anywhere you want an unbroken face.

  The whole face is available for pattern or texture, since no holes interrupt it. Slightly more fragile than a metal loop shank if the material is brittle.

• Toggle

  Back: Usually a shank or a through-drilled channel

  Use it on: Duffle coats, chunky cardigans, bags.

  Elongated so it passes through a loop rather than a slit buttonhole. Pairs with a rouleau or leather loop, not a worked buttonhole.

• Covered button

  Back: Metal shell plus a snap-on back plate

  Use it on: Matching a dress or jacket exactly, and Chinese-ball closures.

  Sold as blank kits in ligne sizes. Use a light fabric — a thick one will not tuck into the back plate, and interfacing the circle first stops the shell showing through.

• Jeans button / tack button

  Back: A pin hammered through the fabric into the cap

  Use it on: Denim waistbands, workwear, bag flaps.

  Not sewn at all. Fitted with a hammer or a press, and effectively permanent — placement mistakes are unrecoverable, so mark twice.

• Stud and snap

  Back: Two-part, set with pliers or a press

  Use it on: Western shirts, baby clothes, bag closures.

  A different fastener wearing a button's clothes. Faster to use than a buttonhole and no good under real tension.

Shop buttons by size and material, or the wider sewing notions and supplies shelf.

Ligne sizing, and what to use where

Buttons are sized in ligne, written with an L. One ligne is a fortieth of a French inch — about 0.635 mm — so you can convert any ligne size to millimetres by multiplying by 0.635, and back again by dividing. A 40L button is one inch across, which is a handy anchor to remember.

Sizing by garment

• Dress shirt: 18L on the front, 16L on collar and cuffs. Sleeve buttons are conventionally a size down from the front.
• Blouse or light dress: 18–24L, depending on how much you want them noticed.
• Trouser waistband: 24–28L, and a flat four-hole button so it sits low under a waistband facing.
• Cardigan: 24–28L. Knitwear needs a shank or a generous thread shank because the fabric is thick and stretchy.
• Blazer: 30–34L on the front, 20–24L on the sleeves.
• Coat: 36–45L, shank type, with a backing button behind each one.

A proportion rule that works: the button should be no wider than half the width of the placket or band it sits on. A button wider than that overhangs and looks tacked on rather than designed in.

Materials and how they wash

Material is mostly an aesthetic choice, with one genuinely practical consequence: whether the finished garment can go in a machine. It is worth knowing before you sew twelve of them onto a shirt.

One practical habit regardless of material: cover buttons with foil or a pressing cloth when you iron. A hot soleplate melts polyester, crazes horn and cracks shell, and it happens the once you were in a hurry.

Thread and needle

A button is rubbed and levered every single time the garment is fastened, which makes this one of the few places in sewing where thread choice genuinely decides longevity.

• Shirts and blouses: all-purpose polyester, used doubled. Four strands total through the holes is plenty for a 18L button in shirting.
• Coats, jackets, bags: buttonhole twist or topstitch thread, single. Thicker, stronger and far more abrasion resistant, and it looks right at that scale.
• Knitwear: polyester, doubled, plus a backing button. Knit fabric has no resistance to a point load and a button will simply travel through it otherwise.
• Skip cotton for anything under real strain. It is lovely thread but it has less abrasion resistance than polyester, and abrasion is exactly what a button does to its own stitching.
• Wax it. Drawing doubled thread across beeswax or a thread conditioner stops it tangling, and adds a real amount of strength and water resistance. Two seconds, noticeably better result.

For the needle, a sharps in size 5 to 8 covers most button work — long enough to grip, fine enough to pass through the holes twice. Use a size 1 to 4 for buttonhole twist, which needs a bigger eye. Needle types and sizes →

Shop sewing thread and hand sewing needles.

Sewing a button on properly

The step that separates a button that lasts from one that does not is the thread shank — a small column of thread between the button and the cloth. It gives the buttonhole layer somewhere to sit. Without it, fastening the garment levers the button sideways against its own stitching.

1. Mark the position. Fasten the garment as it will be worn and push a pin through the buttonhole. Mark where it lands — centred across the buttonhole, and at the end nearest the garment edge, because that is where the button will settle under strain.
2. Anchor without a knot. Two or three tiny stitches on the right side at your mark. A knot is a lump that can pull straight through a single layer of shirting; stitches cannot.
3. Add a spacer. Lay a toothpick, a matchstick or the shaft of a second needle across the top of the button, between the holes. Thicker fabric wants a thicker spacer — a matchstick for a coat, a needle for a blouse. This is what creates the shank.
4. Stitch through. Four to six passes through each pair of holes, over the spacer. On a four-hole button pick a pattern and keep it consistent: parallel bars are the shirt standard, a cross is stronger, a square is decorative.
5. Wrap the shank. Remove the spacer. Lift the button up to the top of its slack, bring the needle up between the button and the cloth, and wrap the thread column tightly three to five times. It should look like a small neat pillar.
6. Secure and bury. Take the needle down to the wrong side, work two half-hitches into the existing stitches, then run the thread a centimetre or two between the fabric layers before cutting. A knot on the surface will find its way loose; a buried tail will not.

Shank height: match it to the thickness of the buttonhole layer, not to the button. Two layers of shirting need barely a millimetre. A wool coat front with interfacing and facing needs 3–4 mm, which is why the spacer gets thicker as the cloth does.

Shank and heavy buttons

A shank button already has its gap built in, so you do not need a spacer — but you may still want a short thread shank on top of it for a very thick coat, and you almost certainly want a backing button.

• Stitch through the loop repeatedly, six or more passes, keeping them stacked in the same small spot rather than spread out. A spread cluster lets the button rock.
• Use a backing button. A small flat two-hole button on the wrong side, stitched through with the same passes, spreads the load across a wider area of cloth. On coats, bags and knitwear this is the difference between a button that lasts the garment and one that leaves a hole. Every good ready-to-wear coat has them.
• Interface behind the button, not just behind the buttonhole. The button side takes the same strain and is routinely left unreinforced.
• Heavy or glass buttons want buttonhole twist and a backing button as standard. Their weight works on the stitching all day, not only when fastened.

Buttonholes that fit

The formula, and it is worth committing to memory:

The thickness term is the one that gets left out, and it is why a domed or shank button will not pass through a buttonhole cut to its diameter. Test the length on a scrap that includes every layer the real buttonhole will have — fabric, interfacing, facing — because the stack changes how much the button has to travel.

Horizontal or vertical

• Horizontal — waistbands, cuffs, jacket and coat fronts, anywhere with sideways strain. The button settles at the end nearest the garment edge and stays there instead of popping.
• Vertical — narrow interfaced plackets with low strain, which is why shirt fronts use them. They keep the placket looking clean and centred.
• If unsure, horizontal. It is the stronger orientation and it is more forgiving of small placement errors.

Cutting and finishing

• Always interface behind a buttonhole. A buttonhole in uninterfaced cloth stretches out of shape within a few wearings. Non-woven or woven fusible both work.
• Cut safely. Push a pin across the inside of each bar tack, then cut between them with a seam ripper or a buttonhole chisel. The pin stops the blade running through the end of your stitching, which is the classic way to ruin a finished garment.
• Seal the cut edges. A dot of fray sealant or a very dilute PVA on the raw edges. Let it dry fully before pressing.
• Sew all buttonholes before any buttons. Buttonhole placement should come from the pattern, and button placement should come from the buttonholes — never the other way round.

Placement and spacing

One rule outranks all the others: put a button at the fullest point of the bust, then space outwards from it in both directions. A closure that gapes there is the most visible failure a button layout can have, and it is entirely a placement problem rather than a fit one.

• Shirt or blouse: 7–10 cm apart. Closer spacing reads as more formal and gapes less.
• Coat: 10–13 cm apart, and usually an odd number of buttons for balance.
• Distance from the edge: the button centre should sit at least its own radius plus a few millimetres in from the finished edge, or it will overhang.
• Other stress points: the waist on a fitted dress and the top of a hip vent on a skirt. Both gape if the nearest button is too far away.
• Check before committing: pin every button in place, put the garment on, and look in a mirror. Sewing twelve buttons and then discovering the spacing is wrong is a genuinely miserable afternoon.

Quick answers

What is the difference between a shank button and a flat button?

A flat button has holes through its face and sits against the cloth. A shank button has a stem or loop on the back and no holes through the front, holding it above the fabric so the buttonhole layer can lie flat underneath. Shirts use flat; coats and thick knitwear use shank.

What does 24L mean?

Ligne — the traditional button size unit, one fortieth of a French inch, about 0.635 mm. So 24L is roughly 15 mm across. Multiply any ligne figure by 0.635 for millimetres. 40L is exactly one inch, which is the easiest anchor to remember.

How long should a buttonhole be?

Diameter + thickness + 3 mm. The thickness term is the one people forget, and it is why a domed button jams in a hole cut to its diameter alone. Test on a scrap with all the same layers, interfacing included.

What thread is best for sewing buttons?

Doubled all-purpose polyester for shirts and blouses; buttonhole twist or topstitch thread for coats, bags and heavy buttons. Wax it first. Avoid cotton on anything under strain — polyester resists abrasion much better, and abrasion is what a button does.

Why do my buttons keep coming off?

No thread shank, a surface knot that worked loose, or cotton thread on a high-strain button. Add a shank with a spacer, bury the ends between the layers rather than knotting on top, and switch thread. A backing button fixes the rest.

Do I need a thread shank on a shirt button?

A small one, yes. Shirting is thin so it only needs the thickness of a needle as a spacer, but even that much prevents the button being levered flat against the placket every time it fastens. On a coat the shank needs to be several millimetres.

Should buttonholes be horizontal or vertical?

Horizontal under strain — waistbands, cuffs, coat fronts. Vertical on narrow interfaced plackets like shirt fronts. Horizontal is the stronger default when you are not sure.

Are corozo buttons machine washable?

Yes. Corozo, also sold as tagua nut or vegetable ivory, is dense palm seed dyed all the way through, so it is stable in a normal wash and does not show a plastic core if it chips. It is shell and horn buttons that need care — both are brittle and dislike heat.

How many buttons does a shirt need?

Typically six to eight down the front at 7–10 cm spacing, plus one per cuff and one at the collar. Work outwards from a button at the fullest point of the bust rather than dividing the placket evenly, which is what causes gaping.